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Vliv světla a sucha na fotosyntézu a vodní provoz podrostních bylin temperátních doubrav
Vitásek, Roman
Woody plants, especially trees, affects the site microclimate. With their physiological manifestations, they influence hydrological and light conditions and, consequently, the composition and abundance of species from the plant community. A dense tree layer lowers the air and even more the surface temperatures. Its mitigating effect is most pronounced on hot summer days. While transpiration lowers air temperature, trees compete with understory for water. While the shade lowers surface temperature of understory, plants, as autotrophic organisms, need enough light for their survival. Therefore, the question arises, which density of forest canopy is optimal for the survival of understory during the global change that brings along increased temperatures and elevated levels of drought. I investigated how understory herbs cope with drought under simulated sparse and dense forest canopy. The focal species, European wild ginger (Asarum europaeum L.) and liverwort (Hepatica nobilis Schreb.), were divided into four groups: two of them were fully watered and two of them droughted. Each of the water regimes were divided in two groups, simulating sparse or dense canopy of woody overstory. The physiological response of plants (such as the rate of light-saturated photosynthesis, stomatal conductance, intrinsic water use efficiency, concentration of non-structural carbohydrates and water potential) on manipulated light and drought conditions was monitored under various levels of drought stress. The mortality was always higher under deep shade than under light conditions, despite different water management strategies of stomatal regulation. The European wild ginger has characteristics of an isohydric type of plant. During drought, it copes with the negative water potential by reducing stomatal conductivity, at the expense of the ability to actively fight water stress by creating assimilates. Under favorable conditions, this species stores starch that allow it to survive even with a significantly reduced rate of photosynthesis. The liverwort is more anisohydric in its behavior. With the increasing intensity of drought and increasing transpiration, it keeps the stomata open and by active photosynthesis it creates soluble carbohydrates for the production of osmotically active secondary metabolites. It has a very low level of stored starch, which can have a negative effect during prolonged drought. The results indicate that light plays an important role for plant survival under water stress. The changing climate brings along not only increased temperatures but often increased levels of summer drought. Therefore, growing in the understory of the dense forest does not always help the plant to survive warming climate.
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Reakce sazenic vybraných druhů dřevin na zaplavení
Ryšavý, Jan
The thesis investigates the response to flooding of five species types of trees occurring in floodplain forests of South Moravia. This work aimed to evauate different lengths of the seedling flooding and examined seedling vitality and mortality. The investigated tree species were summer oak (Quercus robur L.), hornbeam elm (Ulmus minor Mill.), heart linden (Tilia cordata Mill.), hornbeam (Carpinus betulus L.) and field maple (Acer campestre L.). The flooding experiment was conducted from April to July 2022 and at different time intervals (7-14 days) the seedlings were flooded up to the root collar. Control seedlings were not flooded but only watered. 140 seedlings of each species were flooded and were gradually removed from the flood. The results show that relatively low mortality was observed for the flooded trees in all intervals. It was lowest for Quercus robur and Tilia cordata, which were characterized by high vitality in addition to low mortality. Ulmus minor was characterized by moderately vital seedlings. Acer campestre and Carpinus betulus had the highest mortality and their vitality decreased significantly towards the end of the experiment. The hypothesis of Quercus robur's resistance to flooding has been confirmed, which means the seedlings of this tree can probably cope well with flooding even in the conditions of floodplain forests. Tilia cordata also coped very well with flooding. It has probably invested in trunk thickness in response to water stress, adapted to flooding and thus gained a competitive advantage over other tree species. The thesis confirmed the assumption that Quercus robur is a resilient tree species to flooding and Tilia cordata showed higher resilience than expected.
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Study of common bean drought response with the use of leaf optical properties
Svitáková, Lenka ; Lhotáková, Zuzana (advisor) ; Zámečník, Jiří (referee)
The negative effects of climate change have affected the conditions of agriculture areas, which leads to hampered cultivation of crops, including the common bean's cultivation. Changes, such as extreme temperature swings and lowered water availability in soil create a big challenge for today's agriculture in seeking solutions for safeguarding the food security for all people on our planet. The aim of this thesis was to study a wider range of genotypes of common bean to quantify their resistance against lowered water availability in soil, and to establish new approaches for detecting drought stress with the use of leaf optical properties. From the methodological point of view, this thesis connects the leaf optical properties with anatomical and biophysical leaf traits. The common bean (Phaseolus vulgaris) and the tepary bean (Phaseolus acutifolius) were employed as the model organisms. Plants were cultivated in two differing environments - in a greenhouse setting at the Faculty of Science of the Charles University in Prague and on the experimental fields in Colombia at the international research institute for tropical agriculture - Alliance of Biodiversity International and CIAT. There were 48 genotypes included into the field experiments in Colombia. These included genotypes from both Mesoamerican...
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Determination of volatile isoprenoids as water stress markers of spruce resistance against bark beetle
Slušná, Michaela ; Kalinová, Blanka (advisor) ; Hoškovec, Michal (referee)
Isoprenoids are important components of conifer resin and represent an important part of constituted defence system against herbivores and pathogens. Drought is one of the most important factors that influences the tree physiology and resitance. Due to decreased turgor of resin canal cells, the water insufficiency affects the pressure of the resin and thereby the ability of trees to physically prevent pathogen or herbivore invasion by effective outpouring of the resin. In addition, drought can also change the resin composition and thus can influence the quality of volatiles emitted by the tree. The Norway spruce, Picea abies, is the predominant species of production forests in moderate climate zone. Bark beetles, Ips typographus, represent the most important pest species of spruce. In general, pioneer bark beetles use host volatiles to orient themselves toward the tree suitable for colonization and in many species host volatiles synergize bark beetle aggregation pheromones. Thus the host volatile composition could affect significantly host colonization. This diploma thesis studied the influence of drought on the production and composition of isoprenoid volatile organic compounds in 80 - 100 years old spruce trees. Using I. typographus antennae as biological detectors, we also studied which resin...
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Use of laboratory and image spectroscopy to evaluate drought resistance of Scots pine and to distinguish its ecotypes
Raasch, Filip ; Kupková, Lucie (advisor) ; Potůčková, Markéta (referee)
The aim of this study was to propose a non-destructive method for measuring Pinus sylvestris seedlings, to determine whether water stress would be evident in laboratory spectra of pines, to compare whether the response of pines would differ by ecotype, and to investigate whether two ecotypes of Pinus sylvestris could be distinguished using laboratory and image spectroscopy. For these purposes, hyperspectral images of seed orchards from August 2020 were processed and a three-month laboratory experiment was conducted, in which stress from water deficit was induced in two-year-old pine seedlings from the upland and hilly ecotypes. Spectral data were analysed using mixed statistical models, analysis of variance, principal component analysis, training of supervised pixel classifiers, vegetation indices, and linear regression. Based on the analyses, it was found that water stress can be detected in severely stressed Pinus sylvestris seedlings. The most sensitive spectral bands to water content were observed in the region between 1000-2500 nm. The initial response to water stress did not differ by ecotype, but a faster recovery was observed at the upland ecotype after the period of draught. The two Pinus sylvestris ecotypes were distinguished with high accuracy from both laboratory and image spectral...
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Differences in photosynthesis and plant water status between coppice and high forest
Matoušková, Marie
This diploma thesis focuses on comparison of photosynthesis and tree water status between high forest and coppice of Quercus petraea (Matt.) Liebl. Four different types of management were investigated during vegetation season 2016: high forest, coppice on clear-felled site, coppice with standards and seedlings. Methods of leaf gas exchange and water potential measurements allowed to study transpiration, photosynthesis and its response to light and CO2 concentration and leaf water potential. All these physiological parameters were studied as linked to weather conditions and various levels of drought stress. When the soil water was not limiting factor trees in all variants of experiment behaved similarly. However, during mild to severe drought stress the coppice was superior to seedlings and to high forest. It showed higher photosynthesis rate (2.49 umol m-2 s-1) than seedlings (0.86 umol m-2 s-1), both under moderate water stress. Coppice also had higher stomatal conductance and quantum yield of fluorescence than high forest which allowed to higher photosynthetic rates. The lowest value of predawn water potential was in high forest (-3.27 MPa) whereas highest in coppice (-2.01 MPa) which indicated better water availability and lower evapotranspiration demands imposed on coppice sprouts due to their lower height and therefore lower overall aerodynamic conductance. Response of net photosynthesis to CO2 concentration revealed higher carboxylation rates in high forest than in coppice but low stomatal conductance was a reason for overall lower photosynthetic rates in high forest than in coppice. Due to its superiority under water stress coppice forest may be a viable option for forest management on dry sites during the climate change.
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Vliv vodního stresu na výnosové a jakostní parametry zeleniny
Vojtíšková, Jiřina
The two-year experiment (2010, 2011) dealt with the evaluation of yield and quality parameters of vegetables Capsicum annuum L., variety 'SLÁVY F1' and Allium porrum L., 'GIGANTE SUIZO' treated with mycorrhizal product SYMBIVIT in two irrigation modes. The research was conducted as a field experiment. The site was located on the properties of Faculty of Horticulture MENDELU, Mendeleum, Lednice. The positive effect of the mycorrhizal preparation as an intensifying factor was statistically proven in the quality of pepper seedlings. The set parameters were: plant height, stem diameter and increase of the number of leaves. The set parametres in the quality of leek seedlings were: stem diameter, length of the above-ground part, the length of the underground section, weight of fresh roots, weight of roots after drying. The positive effect of the mycorrhizal preparation as an anti-stress measure was proven in the evaluation of yield of peppers in 2011. The positive effect of the mycorrhizal preparation as an anti-stress measure was also proven in the evaluation of yield of the 1st grade quality of peppers in 2011 and in the quantity of nitrates in leek planted in 2010. The positive effect of mycorrhizal preparation as an intensifying factor or as an anti-stress measure on the other evaluated parameters was not proven.
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Crop water stress assessment using remote sensing approach
ERBEN, Jiří
The present thesis deals with evaluation of crop water stress by means of remote sensing. The first part of the research is focused on the assessment of water stress of sunflowers in a laboratory environment using spectral analysis of the reflected radiation and thermography. Leaf of suflowers temperature were evaluated and using them, the index of water stress CWSI were calculated. Reflection of leaf was evaluated in the wavelengths 350 -2500 nm. From these wavelengths spectral indexes were calculated - NDVI (Normalized difference vegetation index) which detect the presence of living green vegetation, WI (Water Index) which serve to calculate the approximate amount of water in the vegetation and RVI (simple ratio vegetation index) which determine the content of biomass or photosynthetic capacity. After that, they were compared with CWSI. Finally CWSI was compared with the spectral data, and from the resulting correlations they were apparent wavelengths, which correlated with given index more or less. The second part is focused on the assessment of water stress in terms of 4th. level catchment, specifically on catchment "Dehtáře" near Pelhřimov. There were primarily evaluated three biggest areas - fields of winter wheat, field corn and TTP.
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Does water stress and interspecific competition contribute to the functional divergence or convergence of wetland plant species?
Műnichová, Radka ; Douda, Jan (advisor) ; Alena, Alena (referee)
This diploma thesis is based on the experiment which took 5 years. In 52 plastic containers were planted four species wetland plants; two species of grasses (Calamagrostis canescens and Deschampsia cespitosa) and two species of sedges (Carex elata and Carex elongata). Three types of water regime were set up with: high, low and fluctuating water level, where the high and low level of water took turns after one year. One year before the data collection the strongest competitor Carex elata was cut out. For the evaluation of the role of water level (environmental stress) and removal of the dominant (competition) we selected two functional trait indicators: specific leaf area (SLA) and leaf dry matter content (LDMC). SLA is an indicator of resource strategies, competitiveness and efficiency of light photosynthesis. Species with high SLA are usually better competitors for light, but tolerate harder the environmental stress. LDMC reflects a plants investment in persistent leaf structures and therefore in nutrient retention. A significant effect of water regime on LDMC was observed in the species Deschampsia cespitosa that had higher average values of LDMC in dry water regime, which is indicating higher investment into persistent leaf structures. And the effect of the dominant removal on SLA, where the values of SLA in the containers without removed dominant were higher. Increased SLA implies increased intensity of competition for light. My diploma thesis supported that specific leaf area and leafdry matter content are important functional indicators different types of stress conditions in wetland communities.
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Determination of volatile isoprenoids as water stress markers of spruce resistance against bark beetle
Slušná, Michaela ; Kalinová, Blanka (advisor) ; Hoškovec, Michal (referee)
Isoprenoids are important components of conifer resin and represent an important part of constituted defence system against herbivores and pathogens. Drought is one of the most important factors that influences the tree physiology and resitance. Due to decreased turgor of resin canal cells, the water insufficiency affects the pressure of the resin and thereby the ability of trees to physically prevent pathogen or herbivore invasion by effective outpouring of the resin. In addition, drought can also change the resin composition and thus can influence the quality of volatiles emitted by the tree. The Norway spruce, Picea abies, is the predominant species of production forests in moderate climate zone. Bark beetles, Ips typographus, represent the most important pest species of spruce. In general, pioneer bark beetles use host volatiles to orient themselves toward the tree suitable for colonization and in many species host volatiles synergize bark beetle aggregation pheromones. Thus the host volatile composition could affect significantly host colonization. This diploma thesis studied the influence of drought on the production and composition of isoprenoid volatile organic compounds in 80 - 100 years old spruce trees. Using I. typographus antennae as biological detectors, we also studied which resin...
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